Partiosanomalaite, commonly abbreviated to PARSA, is a portable military
Electronic Messaging Unit (EMU)1
for use with telephone and radio equipment,
developed around 1984 by Nokia in Finland.
Messages are encrypted with the
Data Encryption Standard (DES)
and sent over standard voice channels, using
Audio Frequency Shift Keying (AFSK).
PARSA was sold by Philips Usfa (NL) as
the UA-8296 and by
MEL (UK)
as the BA-1403 albeit with a different cryptographic algorithm.

The PARSA is the smaller 'brother' of the Nokia
Sanomalaite (SANLA) M/90
originally released in 1983. Together with the Keskussanomalaite
(KESANLA) these units are part of an integrated reconnaissance and command
messaging system (Sanomalaitejärestelmä), that was used during the 1980s
by the Finnish Defence Forces.

The image on the right shows a typical PARSA unit,
as it was used by both NATO and non-NATO countries.
Note that some details of the device have changed over the years.
In particular the keys on the keyboard may be rectangular.

This particular unit has circular keys that are part of a rubber key pad.
It has 33 buttons that hold the letters of the alphabet and some special
functions. Some keys, e.g. on the upper row, have double or even tripple
functions. The button at the bottom left is used to turn the unit ON.

PARSA has a red alphanumeric 16-character LED display and weights ~1 kg.
It is powered by 6 AA-size batteries
or by an external 10-30 V DC source, usually supplied by the radio.
It interfaces with voice-grade
150 to 600 baud equipment and is suitable for HF, VHF and UHF radio circuits.
It and has a 2000 character transmit (TX) memory and a
2000 character receive (RX) memory that can hold up to 8 messages.
The terminal is fully shock- and water-proof [1].

Messages are encrypted with the embedded
DES algorithm
(implemented in software),
which was thought to be sufficiently secure at the time.
The secret encryption key can be entered directly on the keyboard.
Capture of a terminal can not jeopardise the security of a current software key
in use by other terminals, nor can it compromise security of the system at a
future date. For use by non-NATO countries,
Philips Usfa implemented
an alternative encryption algorithm that had been supplied by the US
National Security Agency (NSA).
This algorithm contained a backdoor[2].

As the PARSA sends its messages as a short data burst,
the device can also be seen as a Burst Encoder.

The diagram below shows the layout of the PARSA's front panel.
The bottom half is taken by the 33 rubber keys that are arranged in
the common QWERTY order. Some keys have more than one function.
The key at the bottom left is used to turn the unit ON.
This key also functions as the Shift-key when selecting the functions
that that are printed above some of the keys. The numbers are shared
with the upper row of keys, which are also used to select the desired
function.

After switching the unit ON, the display first shows the
version number of the firmware.
After pressing END you are promted to
enter the current time.
Once the time is entered, press END and the unit is ready for use.
The display now asks to select the desired function.
This is done by pressing one of the key of the upper row.
When done, press OFF to turn the device off (Shift-Z).

Display the current key. Note that only a 4-position hash code (the check group)
will be shown. The actual key will never be revealed.

↑ KEY

Change the key (Shift-KEY).

CON

Configure
Initiate the sequence for configuring the terminal.

XMT

Transmit
Transmit a message.

ENC

Encrypt
Off-line encryption of the displayed text.

DEC

Decrypt
Off-line decryption of the displayed text.

CLR

Clear
Delete memory contents.

↑ DEL

Delete
Delete the message that is currently being displayed (Shift-DEL).

·—

Morse code
Enter telegraphy mode.

END

Terminate the current function and prompt a new one.

Philips UA-8296

The Nokia Parsa was also sold as a re-batched device
by Philips Usfa in The Netherlands
as the UA-8296, in which case the DES
encryption algorithm was replaced by a proprietary one.
The UA-8296 was sold alongside the much larger UA-8295,
which was based on the Nokia SANLA.

The image on the right shows the front cover of the Philips brochure for
the UA-8295 and the UA-8296, as it was released in 1984.
The front page of the brochure carries the title 'Short Burst Terminals',
(i.e. Burst Encoder)
[A].

According to the brochure, the unit is intended for short burst messages,
in order to minimize the chance of
interception and radio direction finding.
It also states that it uses encryption for secure communication,
but nothing is said about the
cryptographic strength of the unit.

The UA-8295 and the UA-8296 are also featured as Philips devices
in the 1986 editions of Jane's Military Communication catalogue [1],
but Philips never actually built any burst encoders.

The Nokia Parsa was also sold by
MEL in the UK, which was in fact
a rebatched Philips UA-8296 (see above).
The unit is mechanically and electronically identical to the
Nokia Parsa, but like with the Philips UA-8296,
the DES encryption algorithm is replaced by a proprietary one.

The Nokia PARSA is housed in a die-cast aluminium enclosure that
consists of a rectangular case with a removable front panel.
The front panel is attached to the case by means of eight recessed
cross head screw around the edges. Remove these screws to get access to the
device's interior.

After the screws have been removed, the front panel can be titled away.
The interior consists of an interface and power unit, which is housed in
the main case, and a processor and I/O board which is mounted to the rear
of the front panel.

The two boards are connected via a fixed 20-way ribbon cable. Apart from the
analogue audio interface, the main unit also contains the battery compartment
that can be accessed via a hinged door at the side. It accepts six AA-size
penlight batteries, which are a tight fit. Removing them can be
difficult, especially if they are swollen.

Always remove the batteries when the unit is stored, in order to avoid
damage from leakage. Note that all batteries, even professional ones, will
eventually start leaking and cause damage. When the unit described here was
found in 2009, the batteries were swollen so much, that they had to be
removed with force. The corrosion
had almost caused damage to the device's interior.

The processor board is built around an Intel P80C31 microprocessor [3],
running at 100 kHz.
The cryptographic keys are stored in a volatile 8KB CMOS RAM chip,
and are retained by a small supercap in combination with the main battery.

Keyboard and display are mounted to the rear side of the board.
The firmware is held in an 8KB EPROM that is removable in order to allow
for upgrades and software modifications. The image on the right shows the
EPROM inside our PARSA unit, which is marked 8296/00, indicating that
it was made by Philips Usfa
in the Netherlands. 1

This also means that the unit described here probably does not contain
DES, but a different NSA-supplied algorithm that was easier to break.
Details about this algorithm will follow as and when they become available.

Philips Usfa sold the PARSA to non-NATO countries under its own name:
UA-8296. Ther extension 00 denotes a specific variant. At the request
of the NSA, DES was replaced by a government friendly algorithm.